Resonance Energy in Benzene Derivatives with a Variable Functional Group

[img]PDF - Authorized users only
Language: English
109Kb
Title:Resonance Energy in Benzene Derivatives with a Variable Functional Group
Creators:
Exner, Otto
Böhm, Stanislav
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 66, 11, pp. 1623-1637
Uncontrolled Keywords:Benzene, <i>Ab initio</i> calculations, DFT, Enthalpy of formation, Resonance energy, Isodesmic reactions, Substituent effects, Arenes

Abstract

Three isodesmic reactions were investigated in which a variable substituent is transferred from a saturated to an unsaturated hydrocarbon residue: ethane → ethene, methane → benzene, ethane → benzene. Their reaction energies could serve as a measure of substituent resonance ability. They were calculated for 31 substituents by the density functional theory (DFT) at the B3LYP/6-311+G(d,p) level, and served as a model for systematic comparison of the DFT energies and experimental enthalpies of formation ∆<sub>f</sub><i>H</i>°(298). It turned out that calculations at this level are more reliable than experiments; they disagree sometimes with ∆<sub>f</sub><i>H</i>°(298) measured at different times and in different laboratories but agree better with the values calculated by simple additive scheme. Some particularly suspicious values were pointed out. The DFT reaction energies of the isodesmic reactions, ∆<sub>1</sub><i>E</i>-∆<sub>3</sub><i>E</i>, were correlated with the standard scales of resonance and with other scales of substituent effects by multiple linear regression and principal component analysis. The three scales are fairly similar to each other (correlation coefficients 0.68-0.83), depend rather strongly on resonance (75% of the variance) but involve still at least one component which could not be explained in terms of common substituent effects. Certainly they do not depend - not even slightly - on the inductive effect, steric effect or polarizability. <p>

Title:Resonance Energy in Benzene Derivatives with a Variable Functional Group
Creators:
Exner, Otto
Böhm, Stanislav
Uncontrolled Keywords:Benzene, <i>Ab initio</i> calculations, DFT, Enthalpy of formation, Resonance energy, Isodesmic reactions, Substituent effects, Arenes
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:66
Number:11
Page Range:pp. 1623-1637
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20011623UNSPECIFIED
ID Code:1881
Item Type:Article
Deposited On:06 Feb 2009 17:13
Last Modified:06 Feb 2009 16:13

Citation

Exner, Otto; Böhm, Stanislav (2001) Resonance Energy in Benzene Derivatives with a Variable Functional Group. Collection of Czechoslovak Chemical Communications, 66 (11). pp. 1623-1637. ISSN 0010-0765

Repository Staff Only: item control page